Demesh S. Many-atom structures and potential scattering of electrons by molecules

This work is devoted to theoretical study of the peculiarities of fragment appearance in electron-impact dissociative ionisation study of sulphur-hexafluoride, methane, ethane and sulphur molecules, as well as to the investigation of potential scattering of electrons by phosphorus, sulphur and antimony molecules and also by carbon and sulphur fluorides. The appearance energy of positively charged ion fragments has been calculated for the above mentioned molecules for the first time. The effective reaction pathways of dissociative ionisation processes are analysed. A good overall agreement is obtained between our calculated energy values and the experimental ones, which were found in the literature. As the number of the fragment products increases the difference between these data also increases. The elastic differential and integral cross sections of electron scattering by the homonuclear phosphorus, sulphur and antimony molecules as well as by the heteronuclear carbon and sulphur fluoride molecules have been calculated systematically. The calculations are provided in a wide collision energy range from a few up to hundreds of eV. The cross sections are in a good overall quantitative and qualitative agreement with the experimental data from the literature above ~30–50 eV. It is emphasized in the work that in order to calculate differential cross sections the more adequate method is the general approximation of the independent atom model, while for calculating the integral cross sections it is better to use the simpler additivity rule. It is also shown that taking into account the absorption effects has less influence on the behaviour and more influence on the amplitude of the cross sections of electron scattering by molecules.